Journal of the Czech Geological Society 51/12(2006)

43

New data on mineralogy of the Vysoký Kámen deposits near Krásno,Slavkovský les area, Czech RepublicNové poznatky o mineralogii loisek Vysoký Kámen u Krásna(Slavkovský les, Èeská republika)(32 figs, 11 tabs)JIØÍ SEJKORA1  PETR ONDRU2  MIROSLAV FIKAR3  FRANTIEK VESELOVSKÝ2  ZDENÌK MACH4  ANANDA GABAOVÁ5
Department of Mineralogy and Petrology, National Museum, Václavské nám. 68, CZ-115 79 Praha 1, Czech Republic
Biskupský dvùr 2, CZ-110 00 Praha 1, Czech Republic
3
Plaská 55, CZ-323 00 Plzeò, Czech Republic
4
Kolová 116, CZ-360 10 Karlovy Vary, Czech Republic
5
Czech Geological Survey, Klárov 3, CZ-118 21 Praha 1, Czech Republic

1

2

Detailed mineralogical study focused on two deposits located on slopes of the Vysoký Kámen hill near Krásno in the proximity of the townof Horní Slavkov in Czech Republic. The open pit exploiting industrial feldspar material (mainly feldspathites and aplitic granites) offerred
new finds of minerals in the Slavkovský les. The following minerals were identified: autunite, bertrandite, beryl, goethite, hematite, koechlinite,kolbeckite, meta-autunite, powellite and scheelite. In the nearby abandoned greisen deposit a phosphate mineral association was observed
consisting of cacoxenite, leucophosphite, vivianite, wavellite and minerals of the chalcosiderite-turquoise and strengite-variscite series. In
addition to them dickite and goethite were identified. The genesis of these mineral associations is discussed.
Key words: greisen; supergene minerals; phosphates; molybdates; wolframates; Vysoký Kámen near Krásno; Horní Slavkov; western Bohemia;
Czech Republic

Introduction
The two studied deposits are both localized on the slopesof the elevation 819.4 m, west and northwest of Krásno,about 7 km south-southwest of Horní Slavkov in western Czech Republic. The first one is an abandoned Sn-W
greisen deposit and the second one is feldspathite (feldspathite = leucocratic alkali feldspar syenite) body exploited presently as ceramic feldspar deposit. The greisen deposit was uncovered by an open pit (Fig. 1), directlyat the NW edge of the Krásno village. During a recultivation the quarry was filled with various rock material.
Thus the supergene* mineralization can be now observed
only on a limited scale at the outcrop of a silicified fault
zone exposed above the former quarry (Fig. 2). The feldspar deposit (called as Vysoký Kámen  feldspar, in thefollowing text) is exploited by a quarry (Fig. 3) with several levels (Fig. 4), located on the northern slope of theelevation 819.4 m, about 0.5 km west to northwest of the
Krásno village.

migmatites. A marginal pegmatite (stockscheider) is often present at the granite contact. The stock has an oval
shape in plan, but the southwestern flank is cut off by afault zone, uplifted and strongly eroded (Fig. 5). A breccia-textured quartz gangue, stained by iron oxides, fills
the fault zone (Fig. 6). Thus, only a low core part of thestock, composed of aplitic granite with greisen relics, ispreserved (Beran 1999).
Coarse-grained topaz-mica greisen builds the remaining part of the stock and downwards it passes to greisenized granite. The greisen body is composed of several
mineral zones with a total thickness of 40 to 60 m. In
the central part, the greisen reaches upwards up to the

Geological situation of the Vysoký Kámen deposits
The greisen stock at Vysoký Kámen is positioned southwest of the Schnöd stock, in extension of a line connecting the Schnöd and Huber granite stocks. It is located in
an intrusion of a younger suite granite, i.e., classified with
the Younger Intrusive Complex granite (YIC granite).
The envelope to this granite body consists of migmatizedbiotite paragneiss, grading to medium-grained, advanced

Fig. 1 Open pit at greisen deposit Vysoký Kámen near Krásno (photo
P. Beran 1986)* note by referee: the term supergene is used in a relatively loose sense, in agreement with common practice in mineralogical literature. Some publications
on ore deposits use the term specifically for a certain part of the oxide zone (zone of supergene enrichment).

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Fig. 2 Relics of open pit at greisen deposit Vysoký Kámen near Krásno after recultivation (photo J. Sejkora 2002)

Journal of the Czech Geological Society 51/12(2006)

granite-gneiss contact. The outcrop of the stock at thepresent surface has approximately 200 by 300 m size,
disregarding the uplifted southwestern part. At the margins the greisen body is split to several smaller parts
which gradually wedge-out and pass to greisenized granite. The greisenized granite directly below greisen isstrongly hydrothermally altered, mainly by kaolinization.
Toward the deeper levels, the alteration dies out and therock passes into a fresh Li-mica-topaz granite. Still todeeper levels, about 150 m below surface, the stock is
composed of a leucocratic topaz granite, which gradually evolved from ordinary granite via the disappearanceof Li-mica. The Sn-W mineralization at Vysoký Kámen
is formed by cassiterite and subordinate wolframite impregnation in greisen and greisenized granite. Miner-

Fig. 3 Quarry at the Vysoký Kámen deposit near
Krásno (feldspar) (photo J. Berger 2001)

Fig. 4 Quarry at the Vysoký Kámen deposit near
Krásno (feldspar) (photo J. Sejkora 2002)

Journal of the Czech Geological Society 51/12(2006)

Fig. 5 Geological section of Vysoký Kámen (greisen) deposit, according to Janeèka in Beran (1999).

Fig. 6 Outcrops of quartz filling of the Vysoký Kámen tectonic fault(photo J. Sejkora 2002).

alized ore shoots are much smaller than the greisen bodies and they are always confined to the greisen interior.
The shape of the ore shoots, as well as of greisen, is very
irregular. The main ore body has a more simple shape andit is located in a distance of 3 to 8 m from the granite
contact.
The feldspathite deposit (Vysoký Kámen  feldspar)
represents a part of the granite stock which is greisenizedat its contacts. At the east the stock is bound against themetamorphic rocks of the Slavkov gneiss roof pendantby a fault trending NW-SE (Vysoký Kámen fault). At thenorth Li-mica-topaz granite occurs, at the west the ibeník type of muscovite granite, and at the east and southeast the stock contacts greisens. Feldspathites show gradual transitions to the enclosing granite, at some places
they form layers, nests and tube-like bodies, at others they
are accompanied by a pegmatite (Beran 1999). The outcrop of the deposit is 250 by 250 m in size. Reserves offeldspathites were measured also at the subsurface levels and extend downwards from the outcrop. Feldspathitelayers, with the best raw-material quality, occur at a depthof 70 m from the surface (about 700 m a.s.l.). Altogether, feldspathite, aplitic granite, aplitic granite with a low

45

mica content and rare pegmatites are exploited as a feldspar raw-material with a low content of iron oxides.
The majority of studied samples was collected at thelower level of the Vysoký Kámen feldspar quarry, near abranch of the fault zone filled in by jasper, quartz andclay minerals. A lenticular body of vein-type greisen,
up to 3 m wide, trending NE-SW and dipping 75 to 80°
SE was also observed there. This body has a core of recrystallized quartz with wolframite, molybdenite, bismuthetc., and an outer zone of muscovite, quartz, apatite, beryland clay minerals formed by greisenization of coarsegrained feldspar. The body has an outer kaolinized rim.
It is probable that the rock is rather a greisenized pegmatite than a vein-type greisen.
Methods of mineral identification
Surface morphology of the samples was studied using
optical microscope Nikon SMZ 1500 in combination withdigital camera Nikon DXM1200F for microphotography
in incandescent light. Details of surface morphology werestudied in secondary electron images with the electron
scanning microscopes JEOL JSM T-20 (Z. Mach; Research Institute of Ceramics, Karlovy Vary  Bøezová)
and Tesla BS 340 (A. Gabaová and J. Sejkora, Czech
Geological Survey, Prague).
The X-ray powder diffraction analysis was used for
identification of minerals. To minimize complicated shapeof background due to classic glass sample holder, thesamples studied were placed on the surface of flat silicon wafer from alcoholic suspension. Step-scanned powder diffraction data were collected using Philips XPert
MPD diffractometer with a metallo-ceramic copper tube
which was operated at high-voltage of 40 kV and tube
current of 40 mA. A graphite secondary monochromator
has been used to produce CuKá1á2 radiation. In special
cases a film methods  Gandolfi camera 114.6 mm (CoKáradiation) were used. The results were processed by using X-ray analysis software ZDS for DOS (Ondru 1993),
Bede ZDS Search/Match ver. 4.5 (Ondru  Skála 1997);
unit-cell parameters were refined by program FullProf(Rodríguez  Carvajal 2005).
We used energy dispersion analyser Tracor-Northern
for qualitative chemical analysis (R. Rybka, Czech Geological Survey, Prague). Additional quantitative chemical analyses were made with the electron microprobe
Cameca SX 100 (J. Sejkora and R. koda, Laboratory ofelectron microscopy and microanalysis of Masaryk University and Czech Geological Survey, Brno). Studied
samples were mounted in epoxide resin discs and polished. The polished surfaces were coated with carbon layer 250 Å thick. Wavelength dispersion mode and operating voltage 15 kV were used in all analyses. Used beam
current and diameter reflect stability of analyzed phases
under electron beam. Stable phases were analyzed under
20 nA current and 2 µm beam size. Less stable and highly
hydrated minerals were analyzed at conditions of 10
4 nA and 1030 µm beam diameter. For smaller aggre-

46

gates (< 10 µm) of unstable minerals the beam diameter
was as large as possible and applied beam current was
only 12 nA. The sequence of elements determination
during analyzing was operatively changed according tochemical composition. Volatile and major elements wereanalyzed prior to stable, minor, and trace elements. Higher
analytical totals of minerals containing higher amount ofhydroxyl or crystalline water were generally caused byescape of water under high vacuum, well documented bya collapse of crystals or by electron beam heating during analysis, causing escape of water, documented as intensively bright spots after analysis. Lower analytical
totals of some samples were primarily caused by the porous nature or by poorly polished surface of soft or cryptocrystalline minerals.
To minimize peaks overlapping, the following analytical lines and crystals were selected: Ká lines: Al (TAP,
sanidine), As (TAP, InAs), Cu (TAP, dioptas), P (PET,
fluorapatite), Ca (PET, andradite), S (PET, barite), Fe(LIF, andradite), Zn (LIF, ZnO); Lß line: Sr (PET, SrSO4);
Lß line: Ba (PET, benitoite); Mß line: Bi (PET, metallic
Bi). Peak counting times (CT) were 10 to 20 s for mainelements and 30 to 60 s for minor and trace elements. CT
for each background was ½ of peak time. When only one
background and appropriate slope had to be used, thebackground CT corresponded to peak CT. Applicableminor to trace elements were preferentially analyzed using high sensitivity large LPET and LLIF crystals. Raw
intensities were converted to the concentrations using
automatic PAP (Pouchou  Pichoir 1985) matrix correction software package.
Infrared spectra were recorded with PYE-UNICAMPHILIPS SP3-300 and Perkin Elmer 521. Spectra were
measured from KBr tablets in the range of 4000200 cm-1,
time 7 minutes (O. ilková, ÚVZÚ, Plzeò).
Minerals identified at the Vysoký Kámen (feldspar)
depositAutunite Ca(UO2)2(PO4)2 . 1012 H2O and metaautunite Ca(UO2)2(PO4)2 . 6 H2OPauli (1990) reported autunite as light yellow powdery
aggregates passing to tetragonal crystals with pearly lustre, up to 3 cm in size. Autunite was observed in a steeply
dipping fracture within the greisen, locally healed byfinely crystalline quartz associated with goethite.
Meta-autunite occurs through the whole profile and at
all levels of the quarry. The most common form is thatof fine and inconspicuous impregnations in fractures ofleucocratic granite and of greisen. Yellowish mixture withclay minerals in cracks and fissures represents anotherfrequent form of meta-autunite occurrence. Imperfect tetragonal tabular crystals or crystalline crusts of light yellow or yellow colours are relatively rare. In a short-wave
and long-wave UV light it shows very strong yellow
green fluorescence. The unit-cell parameters (Table 1)
correspond to the published data.

Journal of the Czech Geological Society 51/12(2006)

T a b l e 1 Unit cell parameters of meta-autunite (tetragonal P4/nmm)
this paper
6.974(1)8.451(2)
411.0

a [Å]
c [Å]
V[Å3]

Makarov – Ivanov (1960)
6.96(1)8.40(2)406.9

Bertrandite Be4Si2O7(OH)2
Bertrandite forms inconspicuous, thick tabular crystals up
to 3 mm in size. They occur in greisen cavities on the
crystals of quartz, rarely in the cavities after leached berylin association with clay minerals, apatite and exceptionally with wolframite. Although the amount of leachedberyl is notable at this locality, bertrandite is a rare mineral. It was also observed as aggregates of transparent
acicular crystals up to 2 mm in size deposited on imperfect crystals of pink-beige apatite. Bertrandite has been
observed close to corroded beryl only rarely, possibly due
to relatively high mobility of Be ions. The unit-cell parameters (Table 2) correspond to published data.
T a b l e 2 Unit cell parameters of bertrandite (orthorhombic Cmc21 )

a [Å]
b [Å]
c [Å]
V[Å3]

this paper
8.720(1)15.2785(9)4.5706(1)608.93

Giuseppetti et al. (1992)
8.716(3)15.255(3)4.564(1)607.0Beryl Be3Al2Si6O18
Beryl is a fairly common mineral in the greisen, as granular aggregates or perfectly formed crystals in vugs ofgreisen and quartz. The crystals are grey-brown, greyblue, light blue, white, or rare colourless translucent up
to 12 cm long and 2.5 cm wide. Some aggregates form
layers up to several dm long, with the grains which werehydrothermally strongly corroded (Beran 1999). Granular beryl aggregates of yellowish or greenish colour are
also very frequent enclosing in places imperfect bluishand grey green prismatic crystals or radiating crystal
groups up to 15 cm long. The occurrences of beryl wereconfirmed by X-ray powder diffraction data.
Goethite FeO(OH)It occurs as spheroidal radiating aggregates and small redbrown crystals in association with koechlinite-russellite,
autunite, meta-autunite and powellite in the cavities of
the quartz gangue. It is the youngest mineral in the mineral associations described. Goethite was identified by
X-ray powder diffraction data.
Hematite Fe2O3
Hematite occurs in radiating spheroidal aggregates composed of microscopic red brown acicular crystals. The

Journal of the Czech Geological Society 51/12(2006)47

aggregates are on average 5 mm in diameter and very
similar to goethite aggregates. This type of hematite wasdeposited in some cavities in quartz and in fractures in
the greisenized granite. Hematite along with goethite belong genetically to the youngest minerals at the deposit.
Hematite was identified X-ray powder diffraction data.
Koechlinite (BiO)2MoO4
Koechlinite is a common mineral in the greisen bodyforming usually powdery coatings and infilling of cavities after leached molybdenite. Imperfectly foliated, ductile crystals up to 0.1 mm are rare. The locality provided
relatively rich samples with yellow koechlinite coatings
several cm2 in size. Koechlinite was formed by decomposition of powellite and Bi was provided by native bismuth,
observed as relics near some koechlinite occurrences.
Unit-cell parameters of koechlinite (Table 3) are in agood agreement with published data. Quantitative chemical analyses of koechlinite (Table 4) show, in addition
to minor As and P contents, also minor W. This indicatesthat the mineral has the composition close to the endmember of the isomorphous series koechlinite (Mo)  russellite (W). Its chemical composition corresponds to theT a b l e 3 Unit cell parameters of koechlinite (orthorhombic Pca21 )

a [Å]
b [Å]
c [Å]
V[Å3]

this paper
5.488(3)16.24(1)5.510(5)491.1

Fig. 7 The infrared spectra of koechlinite from Vysoký Kámen  feldspar, Krásno near Horní Slavkov.

following empirical formula, based on six oxygen atoms:(BiO)2.00(Mo0.90W0.06P0.02As0.01O4). Beran (1999) reported
an occurrence of intermediate members of the russellitekoechlinite series from the same greisen body. However,no analytical data support this information. The infrared
spectrum of koechlinite from Vysoký Kámen is given in
Table 5 and in Fig. 7. Bands at 320 and 720 cm-1 correspond to deformation vibration of the BiO+ ion. Bands
at 320, 440, 795, 835, 1000 and 1070 cm-1 correspond tovibration of the (MoO4)2- anion.
Kolbeckite ScPO4 . 2H2O
Kolbeckite was found in several samples only as blue orgrey blue crystals (Fig. 8) rarely up to 2 mm long, ofTeller et al. (1984)
5.4822(3)16.1986(8)5.5091(3)489.23

T a b l e 4 Chemical composition of koechlinite from Vysoký Kámen(feldspar) (in wt. %)Bi 2O3
As 2O5
P2O5
MoO3
WO3
total

Vysoký Kámen
75.85
0.22
0.40
20.98
2.14
99.56

theoretical composition
76.40

23.60
100.00T a b l e 5 Infrared spectrum of koechlinite from Vysoký Kámen[cm-1]
320
440
570
725
795
835
1000
1070

*
w
w
w
vs
s,sh
s
m,sh
m

[cm-1]
1115
1275
1375
1440
1635
1705
2920
3420

* Character of absorption maxima:
sh – shoulder; b – broad. Intensity scale:vs – very strong; s – strong; m – medium;mw – medium weak; w – weak; vw – very weak.

*
m,sh
m
vw
vw
m
w
w
vw,b

Fig. 8 Dark blue kolbeckite crystal, Krásno (feldspar) near Horní Slavkov, width of figure 2 mm; photo J. Sejkora, Nikon SMZ1500.

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Journal of the Czech Geological Society 51/12(2006)

shortly prismatic morphology (Fig. 9). It occurs in quartz
cavities in association with hematite, apatite and in theproximity of corroded beryl crystals. In a single case kolbeckite was found as an overgrowth on scheelite in aquartz cavity. Scandium for crystallization of kolbeckite
was probably mobilized from wolframite which may contain up to 0.1 wt. % Sc.

Fig. 9 Short prismatic crystal of kolbeckite. Vysoký Kámen  feldspar,
Krásno, width of figure 0.6 mm; SE photo, Tesla 320 (A. Gabaová).

X-ray diffraction pattern of a single crystal of kolbeckite (Table 6) corresponds to the published data for thismineral from Fairfield, USA (Mrose  Wappner 1959).
Some differences in the intensities of diffraction maxima were probably caused by small quantity of material
available for study. Identification is confirmed by microprobe analysis showing the presence of Sc and P as the
major elements.

Meta-autunite Ca(UO 2)2(PO4)2 . 6 H2O
See autunite.
Powellite CaMoO4
Two generations of powellite occur at the studied locality. The older generation forms grey brown to dark brown
flaky aggregates up to several cm long which are thepseudomorphs after molybdenite. This generation of powellite fills small cavities in quartz after leached molybdenite. Large flakes of the first generation of powellite arecemented by finely crystalline light brown powellite of ayounger generation. The younger generation of powellite
forms druses of imperfect bipyramidal crystals (Fig. 10)of brown to grey brown colour with glassy to greasy luster (Fig. 11). The crystals which deposited on quartz are
exceptionally up to 3 mm in size. Druses of imperfecttabular crystals of powellite 12 mm in size are rare. The
first generation of powellite was partly altered to a mixture of koechlinite-russellite, so that these minerals are
regularly observed in a joint occurrence. Unlike koechlinite-russellite, powellite shows light yellow fluorescence in short-wave UV light; however, powellite of thesecond generation exhibits a weak fluorescence.
Unit-cell parameters were calculated for the younger
generation of powellite (Table 7) and show a good correspondence with the published data. The quantitative
chemical analyses (Table 8) show minor abundances ofMg, W, P and As. The empirical formula based on fouroxygen atoms is Ca1.02(MoO4)0.96(PO4)0.04. The infrared
spectrum of powellite is given in Table 9 and Fig. 12.

T a b l e 6 X-ray powder diffraction pattern of kolbeckite
Vysoký Kámen
Horní Slavkov
dobs
Iobs

Fairfield, Utah,
USA*
Itab
dtab

30
30
80
10
60
10
100

6.94
5.20
4.88
4.56
3.80
3.51
2.93

10
10
100
95
75

6.94
5.25
4.88
4.51
3.79

30
10
10

2.66
2.44
2.33

40
10
10

2.08
1.877
1.822

85
65
10
10
10
10
55
10
10

2.90
2.76
2.66
2.44
2.33
2.24
2.07
1.87
1.83

Gandolfi camera 114.6 mm, CoKα radiation.
*kolbeckite from Fairfield, Utah, USA (Mrose – Wappner 1959).

Fig. 10 Imperfect bipyramidal crystal of a younger generation powellite; Vysoký Kámen  feldpar, Krásno, width of figure 300 µm; SE photo, Tesla 320 (A. Gabaová).

T a b l e 7 Unit cell parameters of powellite (tetragonal I41/a)

a [A]
c [A]
V[Å3]

this paper
5.226(1)11.431(2)
312.2

Hazen et al. (1985)
5.222(1)11.425(3)311.6

Journal of the Czech Geological Society 51/12(2006)

49

Fig. 12 The infrared spectra of powellite from Vysoký Kámen  feldpar, Krásno.

The measured absorption bands at 320, 430 and 470 cm-1
correspond to í 2 and í 4 deformation vibrations of(MoO4)2-, a wide high-intensity band at 805 cm-1 corresponds to í3 valence vibrations of (MoO4)2- and anotherband at 860 cm -1 corresponds to í1 vibrations of the
MoO42- anion. Very weak bands at 1640 and 3400 cm-1
are caused by adsorbed water.
Scheelite CaWO4
It is a fairly common accessory in disseminated grains
to 1 mm, associated with beryl, wolframite, koechlinite,apatite and other minerals. Exceptionally, scheelite occurred as well-formed grey crystal 1 cm in size, depositedin a quartz cavity and intergrown with minute kolbeckite crystals (Beran 1999).
Fig. 11 Powellite crystals, Krásno (feldspar) near Horní Slavkov, widthof figure 3 mm; photo J. Sejkora, Nikon SMZ1500.

Supergene minerals identified at the Vysoký Kámen(greisen) locality
Cacoxenite (Fe,Al)25(PO4)17O6(OH)12 . 75 H2O

T a b l e 8 Chemical composition of powellite from Vysoký Kámen (inwt. %)

CaO
MgO
P2O5
As 2O5
MoO3
WO3
total

Vysoký Kámen
28.65
0.01
1.41
0.27
68.74
0.10
99.18

theoretical composition
28.04

71.96
100.00Cacoxenite belongs to relatively common minerals at the
locality. It forms coatings and aggregates in fractures ofa quartz breccia in the Vysoký Kámen fault zone and in
the drill cores from a depth up to 40 m below the present
level.
It occurs as radiating aggregates up to 2 mm in diameter, composed of very fine crystals of golden yellow colour (Fig. 13) deposited in fractures in greisen and quartz.

T a b l e 9 Infrared absorption spectrum of powellite from Vysoký
Kámen[cm-1]
3400
1640
1095
1030
1010
905
860

*
vw, b
vw, b
m, sh
s
s
m,sh
s,sh

[cm-1]
805
695
535
470
430
320

* Character of absorption maxima:
sh – shoulder; b – broad. Intensity scale:vs – very strong; s – strong; m – medium;mw – medium weak; w – weak; vw – very weak.

*
vs,b
w,sh
m
m
m
s

Fig. 13 Yellow crystalline crusts of cacoxenite, Krásno (greisen) near
Horní Slavkov, width of figure 12 mm; photo J. Sejkora, Nikon
SMZ1500.

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Journal of the Czech Geological Society 51/12(2006)

The aggregates are often corroded and at margins theyshow alteration to oxy-hydroxides of iron (limonite). The
mineral was identified by X-ray powder diffraction data.
Minerals of the chalcosiderite CuFe6[PO4(OH)2 ]4 . 4
H2O  turquoise series CuAl6[PO4(OH)2]4 . 4 H2OMinerals of this series are common at the locality, particularly as groups of spheroidal aggregates up to 1 mm
in diameter, in fractures of a greisen, in quartz breccia
and quartz veins.
Semi-spherical aggregates occur isolated (Fig. 14), orin small groups grading to thin crusts with irregular to
botryoidal surface (Fig. 15). The aggregates are brightemerald to bluish green, probably in dependence on
Al/Fe ratio. The surface of the aggregates is formed byplaty crystals (Figs 16 and 17), or rare pale blue aggregates (Fig. 18) of prismatic crystals with acute terminations, which belong to the minerals close to the turquoise
end-member (Figs 19 and 20).
The quantitative chemical analyses show various members ranging nearly within the whole isomorphous series(Fig. 21) and indicating chemical heterogeneity of stud-

Fig. 16 Hemispherical chalcosiderite aggregates; Vysoký Kámen (greisen), Krásno, width of figure 125 µm; SE photo M. Fikar.

Fig. 14 Spherical chalcosiderite aggregates, Krásno (greisen) near Horní
Slavkov, width of figure 20 mm; photo J. Sejkora, Nikon SMZ1500.

Fig. 15 Crusts formed by hemispherical aggregates of mineral of turquoise group, Krásno (greisen) near Horní Slavkov, width of figure
30 mm; photo J. Sejkora, Nikon SMZ1500.

Fig. 17 Groups of chalcosiderite crystals; Vysoký Kámen (greisen),
Krásno, width of figure 125 µm; SE photo Z. Mach.

Journal of the Czech Geological Society 51/12(2006)

Fig. 18 Spherical turquoise aggregates, Krásno (greisen), width of figure 8 mm; photo J. Sejkora, Nikon SMZ1500.

51

Fig. 21 Fe  Al (mol. % of components) in minerals of the isomorphic
series chalcosiderite  turquoise, Vysoký Kámen (greisen).

ied aggregates (Fig. 22). Examples of compositionallyheterogeneous chalcosiderite deposited on the crusts ofcrystallized turquoise were found (Fig. 23). Chemicalcomposition of selected members of the series with empirical formulas is shown in Table 10. The powder
X-ray data agree with the PDF2 database.
T a b l e 1 0 Chemical composition of members of the chalcosiderite
 turquoise isomorphous series from the Vysoký Kámen (greisen) deposit (in wt. %)Fig. 19 Spheroidal aggregate of turquoise prismatic crystals with acutetermination; Vysoký Kámen (greisen), Krásno, width of figure 450 µm;
SE photo M. Fikar.

CuO
CaO
BaO
SrO
ZnO
Fe2O3
Al2O3
P 2O 5
As 2O5
SO3
H2O*
total

1.
8.06

48.56
28.77
14.61
100.00

2.
7.57

3.
11.14
0.03

4.
10.91
0.02

5.
11.78
0.09
0.27
0.10
6.68
31.97
33.85
0.04
0.14
17.38
102.29

0.04

0.25
43.30
2.87
23.85
7.33

31.41
12.58
31.08
0.09

20.22
22.18
32.43
0.14

14.38
99.55

15.53
101.56

16.68
102.57

6.
9.78

37.60
34.90
17.72
100.00* H2O is calculated from stoichiometry, assuming the ideal formulaCuM 6[PO4(OH)2 ]4 . 4 H2O (M = Fe,Al) and charge balance. Empiricalformulae were calculated on the basis of 28 (O,OH).
1. theoretical composition of chalcosiderite CuFe 6[PO4(OH) 2 ]4 . 4 H2O
2. composition showing the highest iron content, corresponding toempirical formula:(Cu 0.95Zn0.03)Ó0.98(Fe5.44Al0.56)Ó6.00(PO4)3.37(AsO4)0.64 (OH)7.96 . 4.00H2O.
3. chalcosiderite showing an intermediate composition corresponding
to the following empirical formula:Cu 1.28(Fe 3.55Al2.55)Ó5.80(PO4)4.00(OH 4)4.00(OH)7.98 . 4.00H2O.
4. turquoise showing an intermediate composition corresponding to
the empirical formula:Cu 1.18(Al 3.73Fe2.17)Ó5.90(PO4)3.92(AsO4)0.01(OH)8.28 . 4.00H2 O
Fig. 20 Detail of turquoise crystals with acute termination; Vysoký
Kámen (greisen), Krásno, width of figure 100 µm; SE photo
M. Fikar.

5. specimen showing the highest recorded Al-content, corresponding toempirical formula:(Cu1.22Ca0.01Ba0.01Sr0.01)Ó1.25(Al5.16Fe0.69)Ó5.85 (PO4)3.92 (SO4)0.04(OH)8.24 . 4.00H2O
6. theoretical composition of turquoise CuAl 6[PO4(OH)2]4 . 4 H2 O

52Journal of the Czech Geological Society 51/12(2006)

Goethite FeO(OH)
Goethite occurs mostly in fractures, dominantly in association with phosphates of the turquoise-chalcosiderite series, as spherical radiating aggregates of small red brown
crystals. It belongs to the youngest minerals at the deposit. The mineral was identified by X-ray powder diffraction data.
Leucophosphite K(Fe,Al)2(PO4)2 OH . 2 H2OFig. 22 Compositionally inhomogeneous aggregate of minority chalcosiderite (light coloured parts, containing about 48 mol.% of turquoise
component) and strongly predominating, compositionally inhomogeneous turquoise, containing 21 to nearly 50 mol. % of chalcosiderite
component. Vysoký Kámen (greisen). BSE image, electron microprobe
CAMECA SX100 (Masaryk University Brno; photo R. koda and
J. Sejkora).

It occurs in a hydrothermally silicified tectonic zone in
the upper part of the greisen quarry. Leucophosphite
forms yellow green to grey yellow crystalline coatingsand crusts on quartz. Less common are the aggregates ofsmall, transparent and highly lustrous prismatic crystals
grown on small quartz crystals (Fig. 24). Also found were
spheroidal greenish aggregates up to 3 mm in diameter,
showing radiating internal structure with drusy crystals
on their surface (Fig. 25). Leucophosphite is document-

Fig. 24 Clusters of small leucophosphite crystals; Vysoký Kámen (greisen), Krásno, width of figure 500 µm; SE photo M. Fikar.

Fig. 23 Compositionally inhomogeneous semispherical aggregate of chalcosiderite containing c. 3639 mol.% turquoise. Well-formed crystals of
turquoise at the margin (dark grey) contain only 1222 mol.% chalcosiderite. Vysoký Kámen. BSE image, electron microprobe CAMECASX100 (Masaryk University Brno; photo R. koda and J. Sejkora).

Dickite Al2Si2O5(OH)4
Dickite is a frequent mineral at the deposit. The oldest
generation of dickite formed during the late stages ofhydrothermal mineralization. However, some dickite samples could have been of supergene origin. It forms beige
white soft aggregates, deposited on a crust of light blue
turquoise. Dickite coatings several cm 2 in size coverquartz crystals in the cavities or turquoise-chalcosiderite
crusts. The mineral was identified by X-ray powder diffraction data.

Fig. 25 Clusters of leucophosphite crystals, Krásno (greisen) near Horní
Slavkov, width of figure 7 mm; photo J. Sejkora, Nikon SMZ1500.

Journal of the Czech Geological Society 51/12(2006)

53

T a b l e 1 1 Infrared absorption spectra of leucophosphite from Vysoký Kámen[cm-1]
3430
3310
2950
2920
2850
1640
1460
1380
1150
1070
990
840

*
s
s
vw
w
vw
m
w
w
s,sh
vs
vs
m

[cm-1]
795
775
630
610
590
550
460
425
360
300
232
208

*
w
vw
vs
s
s
m
s
s
m
w
m
m

white coatings with a botryoidal surface and a radiatingfibrous internal structure. Grey and light violet spheroidal aggregates 1 to 2 mm in diameter (Fig. 27) and witha drusy surface, composed of pyramidal crystals 0.1 mm* Character of absorption maxima:
sh – shoulder; b – broad. Intensity scale:vs – very strong; s – strong; m – medium;mw – medium weak; w – weak; vw – very weak.

Fig. 28 Light violet, radiating spheroidal aggregate of strengite;
Vysoký Kámen (greisen), Krásno, width of figure 2 mm; SE photo
M. Fikar.

Fig. 26 The infrared spectra of leucophosphite from Vysoký Kámen(greisen), Krásno.

ed from the association with the minerals of the turquoise-chalcosiderite and variscite-strengite series. The
mineral was identified by X-ray powder diffraction data.
The infrared absorption spectrum of leucophosphite isshown in Table 11 and Fig. 26.
Minerals of the strengite FePO4 . 2 H2O  variscite
AlPO4 . 2 H2O series
Members of the variscite-strengite series occur along
fractures and in the cavities of greisen as minute grey

Fig. 27 Yellowish spherical aggregates od strengite, Krásno (greisen),width of figure 10 mm; photo J. Sejkora, Nikon SMZ1500.

Fig. 29 Detail of the surface of spheroidal strengite aggregate composedof pyramidal crystals; Vysoký Kámen (greisen), Krásno, width of figure 300 µm; SE photo M. Fikar.

Fig. 30 Spheroidal aggregates of pyramidal variscite crystals deposited on quartz crystals; Vysoký Kámen (greisen), Krásno, width of figure 5 mm; SE photo A. Gabaová.

54

Journal of the Czech Geological Society 51/12(2006)

Fig. 31 Detail view of an aggregate of pyramidal variscite crystals;
Vysoký Kámen (greisen), Krásno, width of figure 1.1 mm; SE photo
Z. Mach.

long (Figs 28 and 29), occur in association with leucophosphite and chalcosiderite. The morphology of thevariscite crystals is shown in Figs 30 and 31. The minerals of this isomorphous series have been identified inaddition to X-ray powder diffraction also by semiquantitative chemical analyses. All the samples analyzed contain Al and Fe. Pure end members of the series are unknown at this locality.
Turquoise CuAl6[PO4(OH)2]4 . 4 H2O
See minerals of the series chalcosiderite-turquoise.
Variscite AlPO4 . 2 H2O
See minerals of the strengite-variscite series.
Vivianite Fe3(PO4)2 . 8 H2OVivianite was observed rarely in cavities, deposited onwhite quartz grading to amethyst in the fractures of jasper and in the greisen in the southern part of the quarry.
It forms typical radiating aggregates composed of dark
blue green to black green crystals (Fig. 32) with acutetermination, which are up to 3 mm long. Vivianite occurs in association with cacoxenite, minerals of the turquoise-chalcosiderite series and strengite-variscite. Vivianite was identified by X-ray powder diffraction.
Wavellite Al3(PO4)2(OH,F)3 . 5 H2OWavellite occurs in association with other phosphates asgrey white coatings with a fibrous internal structure. Exceptionally it forms radiating aggregates with older turquoise or chalcosiderite in their centres. Wavellite belongs to the youngest phosphates at the deposit. It was
identified by X-ray powder diffraction.

Fig. 32 Dark blue groups of vivianite tabular crystals, Krásno (greisen), width of figure 10 mm; photo J. Sejkora, Nikon SMZ1500.

Interpretation of supergene mineral assemblages at
the Vysoký Kámen deposit
Vysoký Kámen (feldspar)
Weathering processes, which took place at this locality
and resulted in formation of supergene minerals, represent several distinct sets of conditions. In a general way,
they include a range of processes from probably late hydrothermal to supergene (recent). Leaching and decomposition of beryl, molybdenite and wolframite belong toan early episode of alteration. The resulting supergene
minerals, including bertrandite, powellite (in pseudomorphs after molybdenite) and scheelite belong to the oldest
ones. They are followed by a younger generation of powellite and by kolbeckite. Koechlinite-russellite, autunite
and meta-autunite belong to the latest stages of supergene
alteration. Koechlinite-russellite replaced powellite; Bi
necessary for crystallization of this mineral was provided by native bismuth. There are indications for several
generations of koechlinite-russellite, autunite and metaautunite. Thus, an early generation of autunite crystals
was observed in cavities with quartz. The youngest generation of meta-autunite occurs relatively often as an inconspicuous phase in aggregates of clay minerals. Younger
koechlinite-russellite occurs in small cavities after leachedmolybdenite. The youngest mineral in this association isgoethite, observed in some vugs and along fractures.

Journal of the Czech Geological Society 51/12(2006)

55

Vysoký Kámen (greisen)

References

A relatively simple association of phosphates formed ina breccia zone, partly healed by quartz, and in neighbouring parts of fractured greisen. Leucophosphite, as the oldest mineral, and members of the variscite-strengite series
are probably related to a closing stage of hydrothermal
alteration. Younger phosphates of the turquoise-chalcosiderite series occur in fractures of greisens and quartz
gangue. The complicated compositional zoning in minerals of the variscite-strengite and turquoise-chalcosiderite series indicates significant changes in chemical composition of solutions, including especially variation in the
Al/Fe3+ ratio. Cacoxenite, vivianite and goethite, as the
youngest members of this mineralization, indicate absolute dominance of Fe3+ above Al3+ during the closing stages of supergene mineralization at this locality.

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Be4Si2O7(OH)2, from Val Vigezzo (NO) Italy: the X-ray structuralrefinement.  N. Jb. Miner. Mh., 1319.
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Acknowledgements. The present authors thank Pavel Beran (Regional Museum, Sokolov), Radek koda (Faculty of Science, Masaryk University, Brno), Jiøí Litochleb(National Museum, Prague) and Stanislav Vrána (Czech
Geological Survery, Prague) for co-operation on thisproject. Our thanks also go to numerous colleagues, wholoaned or provided samples for study  Anna Sabová(Kvìtná), Ctibor Süsser (Sokolov), Jaromír Tvrdý (Karlovy Vary) and others. This study was financially supported by the Ministry of Culture of the Czech Republic(Project MK00002327201) a Granting Agency of the
Czech Republic (Grant No. 205/03/D004).
Submitted July 12, 2006

Nové poznatky o mineralogii loisek Vysoký Kámen u Krásna (Slavkovský les, Èeská republika)
Podrobný mineralogický výzkum byl zamìøen na dvì loiska lokalizovaná na svazích kóty 819,4 m Vysoký Kámen u Krásna (u Horního Slavkova,
Èeská republika). V materiálu z èinného lomu tìícího ivcovou surovinu (zejména feldspatity jako souèást pnì granitu mladího intruzivního komplexu)
byly zjitìny autunit, bertrandit, beryl, goethit, hematit, koechlinit, kolbeckit, meta-autunit, powellit a scheelit. Na oputìném greisenovém loisku bylavedle dickitu a goethitu zjitìna minerální asociace fosfátù zastoupená kakoxenem, leukofosfitem, vivianitem, wavellitem a minerály série chalcosiderittyrkys. V práci je podána i struèná interpretace vzniku popisovaných minerálních asociací.